schneider



E. SCHNEIDER v TRANSMITTING APPARATUS UTILIZING THE PRINCIPLE OF THEWHEATSTONE BRIDGE Flled Jan 4, 1922 April 26,1927.

2 '1927. 4 .6 6560 Apnl E. SCHNEIDER TRANSMITTING APPARATUS UTILIZINGTHE PRINCIPLE OF THE WHEATSTONE BRIDGE Filed Jan. 4, 1922 I 3Sheets-Sheet 2 ril 26 1927. 6,560 AP E. SCHNEIDER TRANSMITTING APPARATUSUTILIZING THE PRINCIPLE OF THE WHEATSTONE BRIDGE Filed Jan. 4, 1922 3Sheets-Sheet 3 V A Y Oz llwen/m' J Y J Patented Apr-[ 2 I Y -T IEE;

,OFFI E A;

UGENE SCHNEIDE -or mm, FRANCE, lissmnon To SCHNEVIIDEJR & CIR, or PA IS;

FRANCE, A LIMITED Jornr s'ro'ox COMPANY or FRANCE.

TRANSMITTING APPARATUSFUTYILIZINGF THE PRINCIPLE or ,TH E WHEATSTONEJBRIDGE. i Y I V Application filed January 4, 1922, Serial No.526,984,11111 in France June 15, 1921.

It is known that in all the transmissions utilizing. the classicalarrangement of the NVheatstone bridge the carrying out of an order whichis transmitted is effected by bringing the needle of a voltmeter backtozero;

l'Vhen it isdesired to have a high de gree of precision, .it isnecessary to bring the degree of sensitivity-ton maximum by suppressingthe additional resistance which is usually introduced in series with themovable coil of all the voltmeters; Itvfollows that the resistanceconsistingvot'v the circuit which comprises the coil of the voltmeterand the anus of the bridge'is subjected to unportant variationsaccording .to

the position of movable contacts along two rheostats whlch are used'faspotentiometers,

and that therefore for one and the same displacement between thepositions of the pointers of the transmitting and receiving device, thedeviationsof the needle of the voltmeter may be very dilierent from eachother. "This is a serious drawback because the deviations of the needle,under these conditions,-do not give the operator of the receivinostationan idea ofthe angular dis.

tance which he hasto'correct, and this idea is indispensable in orderfl'Ol him to deter mine the speed at which he should move the adjustableparts in order to properly re turn the needle to zero position."

The main object of the invention is to do away'wlth the above,drawbaclga'nd to maintain the sensitivity constant-in such a manner asto keep proportionality :between the deviations of the needle of thevoltmeter and the displacements to be corrected, bringing' the degree ofprecision to a maximum,

the means which are used consistingin auto-i matically introducing 1nthe circuit of the voltmeter compensating resistances, the

value of which is adjusted according to the position ofthe movablecontacts on: the;

rheostatswhich are used aslpotentiometers. These movable contacts arepreferably adapted to indicate to the operators at each station theorders which are being transmitted'and maybe provided, for'example,withsuitable graduated scales or dialsffor this purpose.

The present invention allows, in addition,

of ensuring a continuity of indications when applied to abridge with twocontacts with a voltmeter havingtwo coils such as de-' scribed in the U.S. Patent No.*l,-LO9,586 of March 14, 1922. a a; i I

'flhe diagrammatical Figure 1 shows how theinvention maybe carried outin the case when "use isl made of atransmission with lVheatstone bridgeofthe usual type, and] such as described in the patent referred toabove.

I Theidiagrammatical Figure 4' shows how the 'compensatingresistancesmay be de-f terminedin' the case of Figure3, and illustrates the valueof the current flowing through the two voltmetercoils,

The diagrammatical Figure 5 shows how,

the compensating resistances may be constructed in the case of Figure 3.

Figure 6 shows a'modiiication in the arrangement illustrated in Figure3.

Figure? diagrammatically illustrates another embodiment of thearrangement shown in Figure 3.

usedas potentiometers respectively at the transmitting and receivingstation and which are fed by the battery E.

FG and H I are two movable con tacts rubbing on the one side on A 13 andFigure 8 is a longitudinal sectional view 01 the resistances andcontactpoints dia- CDand on the other side on thecompem satingresistances J -K and L -M. p

N is a controlling voltmeter situated at the receiving station andconnected at O and P, 'byymeans of a suitable bridgewire, atthe middlepart of the compensating resistances of i the orders transmitted act-lyas in the case of an ordinary bridge needle N is at the zero, has beendisplaced by displacing H-I in such a manner as through a very smallquantity d introducto bring the needle of N back to zero. ing anelectro-motive force 6 in the complex Let R be the resistance of each ofthe comcircuit which the voltmeter feeds it is pospensatingpotentiometrical rheostats A-B sible to adn'iitwithout any appreciableerand C D, 2" the resistance of the coil oi ror that we get GIIIQ? andPl:OG:g the voltmeter, a the partial resistance A F The intensity of thecurrent producing and y the partial resistance OG. a displacement of theneedle N would be If we suppose that HI after having given under theseconditions, by the equabeen brought in the position for which the tion:

The electro-moti've force 6, put in play, sistance il- O li (seeFigure 1) may be acts in a circuit which comprises the resistconstructedby utilizing a rheostat with con ance '2' oi the voltmeter plus twotimes the retacts With this arrangen'ieut the sensitivity sistance y.and which is closed for the one is no longer strictly constant, but itis easily part, by llCAl" and "for the other part, possible to limit thesaid variations at an acby HDBG. The resistance of HCAF being ceptablerate (for example 10%) by adopt- 2a', and the resistance of HDBG beinging a sufficiently number of contacts. fill-50), the combined resistanceof these The successive resistances 1 y 3 f 2 two branches will bedetermined by applying the formula (5) tor the values of incorresponding to the 6 5 centres ot the contacts 1,2,, 3, 4:, it will benoticed that the 'l'unction y has an and COIlSQqUQRtly the current 2'which passes axis of symmetry for through the voltmeter is equal to thevalue R set ttorth in the eipiation above. 5

In the case which has been considered, in order that the constant of thesensitivitv 1t ls Posslble to lntarcmmect two y two shall be. obtained,it is necessary that the h Contacts T -yvalues f n be determined i f tisituated at equal tliStdnie lr'on'i the centre of a? in such a mannerthat itshall remain l n RS Show? j Oi: constant \\liate-.'er a may be.In particular. p l the conshuctlon y e s for y half the number oi?elementary res-aistances ,55 S, S inserted between the con- R 20 tacts.

It will be also noticed that the central We t. y :0 and contact may bereplaced by a sector, because 6 y varies very slowly when a2 has valuesin R R the nelghbourhood of T 2 In the case of Figure 3, i i-l3 and 0-DB b tit ti thi value f i (1) We show the rheostats which are used aspotenget tlometers at the transmitting and receiving stations and whichare fed by the battery E F G and H show a first series of two movablecontacts rubbing on one side on AB and CD, and on the other side on thecompensating resistances JK and L -M F G and H I are a second series o'ttwo movable contacts which always remain diametrically opposite to thefirst contacts. In order to facilitate the description, it 9J (5) willbe admltted by way of example that the potentioineters and compensatingresistances This equation gives the law according to have a developmentof 270 and that they which the con'ipensating resistances should areprolonged by sectors such as A A and be determined in order that astrictly constant B-B leaving between them a free interval sensitivityshall be obtained. of 10.

Figure 2 shows how the compensating re- The carrying out of orderstransmitted by that is:

and

a simultaneous displacemento'f il G? and F -Gc will be effected bysimultaneously" displacing H I and TI -1 in such a .ananner as to bringback to Zero the "needle of the voltmeter N which comprises two coils Tand T The compensating must in this case be determinedin'such a s [somanner that for, a very-"small angular displacement cl between thepositions. of; the pointers at the transmlt-tlng and receiving stations,the sum of the intensities i and i which pass respectively through V theframes T and'T shall remainpractically constant whatever the value of :1maybe.

For this purpose it is "possible to admit for instance that theresistances and 4 will be chosen in such a manner that i and i? followthe laws of variations whichare illustrated in function of theangula'rdisplacement of F l bythe diagrams of Figure 4-, in which the dottedlines correspond to 5 the 'brokenlines to 'P a-ud the dot and dashlines, to the sum c i-1Z I The. said figure. shows that as long as F e-G1s situated between B and A or; between A andA, the frame T alone 18 inact-ion, the sensitivity having then, a value which is proportional to Z(maximum ofi From 459 to 135, the action of T goes decreasing while thatof T goes increasing, and the sensitivity is equal to Zxl, 1. Fron'i to180,xtl1e-lrame T 1 remains alone in service and the sensitivity isequal to Z. I Owing to symmetry the same cycle 'is obviously reproducedfrom 180, the action of T? being replaeedby that of T and vice versa.

The'values of 1 corresponding to predetermined value of 13 or i will bedeter mined by points from the equation (1). I Anyother law of variationmay of course be chosen for i and i on the sole condition that the sumof i and shall remain practically constant. I c ,7

The arrangement illustrated m Figure 3 allows not only of mainta ningthe sensitivity constant during the normal operation of 1 thetransmission, but also of obtaining tw special advantages in the case oftemporary stopping of the operation of the re ceiver." In order; toemphasize theimportance of these advantages we shall examine first ofallfwhat are the difficulties which may arise in the case whenthecompensating resistances, would be replaced by rings of J terminalsand when the sectors A-A, B, C-C, Dc-Di would be suppressed which wouldbring the arrangementto the one described in the U.-

Patent 1,409,586

, dated March 14, 1922.,

If we suppose the receiver, to be temporarily kept in a position suchthat H shall be out), it willbe seen first of all that if F i hasbeendisplaced upwards through in such manner as to bebrought on B, the

resistances y and current willbe sudde'nly reversed'in the" frameT'.Then it will be seen that by supposing the receiver to be kept fixed ina position such that H" shall be in the cuttingofi' zonein the immediateneighbourhood of C,-if F has beendisplaced downwards, the current in Twould bealso cut ofi'as soon as F has arrived on B, that is, as soon asF will have been displaced through 90.

Thereforefthere would be a danger in the case when the displacementbetween the,

transmitting and the receiving stations would acc dentallyexceed 90,that no more indicatlons would bereceived at the receiviliig station orthat the indications which would be received would beerroneous' for theplacing of the two stations in'agreement' with each other. Moreover, ifV is the feeding voltage, in'the case when H" would be, maintained on C,and Fon B, the frame T"'would be traversedby a current, the

intensity'of which Wouldreach therefore it could become overheated, andin any case this would produce, at themoment of closing the current, aviolent shock of the needle of the voltn' eter against its stops, whichshock would be capable, damaging the apparatus. v I v I Letnsj nowconsider the case of Figure 3. It will be immediately seen that theouttingofi' position (corresponding to the displacement between A and B)being rel.

duced to 10 a displacement" of g at least 170 would be necessary inorder thatthe cur-f rent shall be simultaneously cut-off in the ifrepeated, of

two frames. MOl' iovel, it will be seen-that I if F isebrought'onBwhenHis on G or on C, ,thenthe current which traverses the frame T willbelequal to 7".+ ZYWL;

' the frame T (which would have a tendency to reverse the direction ofthe normal deviation. of thevoltmeter) remaining equal to .Y Q r+2Ym thecurrent in the frame would be equal t0 T39 79 2.7018

since, as it hasalready been pointed out, the compensating 'res1stance111 the neighbour- Lil corresponding to 10.

In order to avoid the reversing of the deviation, it will therefore besullicient it the following condition is fulfilled.:

In Figure 3, it is of course possible to substitute resistances tor thesectors which prolong the potention'ietrical rheostats and thecoi'npensating resistances.

It is also possible to replace each oi the systems having two reistanccssuch as J-O and Ol\l by a rheostat with contacts such as the one whichis illustrated in Figure 5. and which similar in every respect to thatshown in Figure Figure (3 illustrates a modification of Figure 3 inwhich the cutting-oft zone has been entirely suppressed by replacing thesectors such as A-A and .I.l by suitable resistances. Forsin'rplii'ication purposes, only the. transn'iitting station has beenillustrated; it will be noticed that the re sistances replacing thesectors retain to B, J to K and J to K The vorltiiiig of this device isin all points similar to the one of Figure 3, with this peculiarity thatthere is no longer a cutting oil zone and that the reversing of thecurrent in the frames is more progressively effected.

In the arrangement shown in Figure 6, the compensating resistances maybe replaced by rheostats with contacts, such as the one illustrated inFigure 5.

Fig. 7 illustrates another embodiment of the present invention whereinthe resistance L, P, M, of Fig. has been replaced. by the type ofresistances shown in Fig. It is to be expressly understood that theresistanees shown in Fig. 5 may replace the annular resistance J, O, K,shown in the left-hand halt of Figs. 3 and 7, or vice versa.

In the case when several receiving stations have to be operated by meansof one transmitting station, it will be advantageous to make use of thedistributor described in the U. S. Patent 1309.586 which allows 0talternately and successively connecting each oi the receiving stationswith the transmitting station.

It is often necessary in the application of distant transmissions to beable to introduce a certain displacement between the pointer of thetransmitting station and the pointers of the receiving stations. way ofeX- ample, it may be mentioned that when the transmission is applied tothe telepointing in directionof artillery guns, it may be necessary toadd the corrections of parallax and deflection of the tangent-sight tothe angle of sight.

The above arrangements allow of obtaining in a very simple manner theresult which is looked after, on the condition that the compensatingresistances shall be rendered mechanically integral with thepotention'ietrical rheostats. Indeed itis then sullicientto displacetogether at the transmitting and receiving stations, through the desiredangle, the potent-iometers and the compensating resistances relativelyto the movable contacts which remain connected. respectively with thetelescope (transmitting station) and with the guns (receiving station).

Figure 8 illustrates one manner in which the potentiometer andcompensating resistances may be displaced relative to the movablecontacts. In the form shown, the potentiometer A B, and the resistancesJ 2 K and .l It are mounted on a common support 10, which in thisinstance is a flanged drum provided on its periphery with a worm wheel1.1 which is engaged by a worm \V. 'The drum 1.0 is loosely mounted onshaft S. liligidly secured to said shaft are the conl'tlt'ls F G F GRotation of worm W results in a displacement of the potention'ieter andresistances relative to said contacts.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be perlormed. I declare thatwhat I claim is l. -r transn'iitting system based on the principle ofthe \Vheatstone bridge comprising transmitting and receiving stationbridge resistances forming the arms of said bridge. connections betweensaid stations to complete said bridge including a bridge wire having anindicator therein. compensating resistances in said bridge wire. andindicating means at each station including means for 'arying the.relation of the resistances in the ln'idge arms and for changing theamount of compensating resistance in said bridge wire in accordancetherewith to cause the deviations of the indicator to remainproportional to the displacements between the indicating means of thetransn'iitting and receiving stations.

:2. A transmission to a distance comprising 'trai'ismi-tting andreceiving station resistances forming the arms of a \Vheatstone bridge.connections between said stations to complete the bridge including abridge wire having a voltmeter therein, compensating resistances in saidbridge wire, and means at each of said stations for simultaneously var ving the relation of the resistances in the bridge arms and for changingthe amount of compensating resistance in said bridge wire in accordancetherewith each of said compensating resistancesincluding a sector,

two i series of contacts synnnetrically arranged relative to saidsector, a plurality oi conductors connecting said contactstwo bytWo, anda' series of elementary resistances inserted between said coiuluctors,the sum of said elementary resistances corresponding for each contactto'the valueot the compensating resistance. r

3. Apparatus of the class described comprising transmitting andreceiving station annular resistancesforming the arms of a \Vheatstonebridge, a receiving station voltmeter havlng twofcoils, connectioi'isbetween said stations to complete the bridge including a pair of bridgewires each having one of said coils therein, compensating resistances ineach of said bridge wires, and diametrically disposed movablecontacts atsaid stations forvarying the relation of the resistances in the bridgearms and for chang ing the amount. of compensating resistance in each ofsa d bridge wires in accordance therewith to cause thedeviations of thevolt- 'meter needle to remain proportional to the displacements betweenthe movable contacts at the transmitting and receiving station and 'toprevent .thereversing of the indications of said needle. v y r y 4.Apparatus of the class described co1nprising annular transmitting andreceiving station resistances" forming the arms of a Wheatstone bridge,a receiving station volt-f meter having two coils, connections betweensaid stations to complete the bridgeincludmg a pair of bridge wires eachhaving one of said coils therein, movable bridges at each of saidstations carrying diametrically. disposed contacts for varying therelation of the resistances in said bridge arms and changing the amounto'fsaid Compensating resistance, the latter being such that abnormalheating of said coilsis prevented, and

sectormeans for prolonging the angular de-,

velopment of said annular resistances for the purpose of increasing theangular dis lacem'ent through which one movable bridge may be movedrelative to the'other tive to said movable contacts.

without simultaneously cutting oil the current in said coils. I i

5. Apparatus of the class described com-' prising transmitting andreceiving station resistances forming the arms of a -lVl1'eatstonebridge, a receiving station indicator having twocoils, connectionsbetween said stations to complete the bridge including a pair of bridgewires each having one, of

said coils therein, compensating resistances in said bridge wires, andcontact means at,

each station for varying the relation of the resistances in the bridgearms and for changin;

rlQl'lClgG wires in accordance therewith to cause the deviations of saidindicator to remain proportional to the displacement between saidcontact means, said compensat ing resistances including one or moreseethe amount of compensating resistancein tors, two series of contactssymmetrically" arranged relative to one of said sectors, a

plurality of conductors connecting saidconpensating resistances in saidbridge wire and immovably secured to said bridge resistances, means,including movable contacts, at each station for varying the, relationbetween the resistances in the bridge arms and for changing the amountof compensating resistance in said bridge wire to cause the deviationsof said voltmeter to remain proportional to the displacement betweensaidmovable contacts, andmeans for moving said bridge resistances andcompensatingresistances rela- In testimony er I have sig edthisspecification. ,r

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